1. Field of the Invention
The present invention relates to a vehicle lighting apparatus such as motor vehicles, and more specifically, to a vehicle lighting apparatus comprising means for controlling deflection angle of a lamp for varying the direction of radiation of beam of light corresponding to the traveling conditions, for example, an adaptive front-lighting system (hereinafter referred to as AFS) for vehicles, wherein a correct direction of radiation corresponding to variations in vehicle speed can be set.
2. Description of the Related Art
The AFS proposed for enhancing driving safety of motor vehicles detects information on the steering angle of the steering wheel SW of the motor vehicles, the vehicle speed, and other traveling conditions of the motor vehicles by the sensor 1, and the detected output is input to the electronic control unit 2 (hereinafter referred to as ECU) as shown in FIG. 1. The ECU 2 controls the swivel type lights 3R, 3L provided respectively on the left and right of the front portion of the motor vehicle, that is, the headlamps 3 that the direction of radiation can be deflected in the lateral direction based on the supplied sensor outputs. Such a headlamp may include, as a structure that can turn the reflector provided in the headlamp in the horizontal direction, a structure that can turn the reflector by the driving source such as a motor or the like. A mechanism for this turning is referred to as an actuator in this specification. According to the AFS in this type, when the motor vehicle travels on the curved road, the portion of the road ahead of the curve may be illuminated corresponding to the traveling speed of the motor vehicle, thereby effective in improving driving safety.
However, in the AFS of this type, it is normally preferable to illuminate the area immediately in front of the motor vehicle during travel at a low speed, and to illuminate the front area at a corresponding distance during travel at high speeds. However, in the AFS in the related art, the maximum deflection angle of the direction of radiation is not specially considered, and the maximum deflection angle of the headlamp is uniquely defined, for example, by the steering angle of the steering wheel during travel both at low speeds and at high speeds. Therefore, if the AFS is set to illuminate correctly at the area immediately in front of the motor vehicle during travel at low speeds when the steering wheel is turned by a prescribed angle, the area that is significantly laterally misaligned with the area at a corresponding distance in the traveling direction of the motor vehicle is illuminated during travel at high speeds, which disables the correct illumination by the AFS. Especially, significant change in the direction of radiation during travel at high speeds, during which the steering wheel is to be turned little by little, causes a problem in traffic safety. In contrast to it, when the AFS is set to illuminate correctly during travel at high speeds, it cannot illuminate the area immediately in front of the motor vehicle correctly in the traveling direction on the curved road during travel at low speeds.
When the AFS is activated by turning the steering wheel steeply while the motor vehicle is moving at speeds as low as crawling or coming to stop, especially when parking the motor vehicle in the parking area or putting it in the garage, the direction of radiation of the headlamp is deflected significantly in the lateral direction, and thus the area immediately in front of the motor vehicle in the traveling direction cannot be illuminated, which leads to the unfavorable conditions in terms of the safety confirmation. In addition, a large deflection of the direction of radiation of the headlamp in a state in which the motor vehicle is almost coming to stop is unpleasant for the occupant, and there may be a case in which it dazzles motor vehicles or pedestrians passing nearby, which may be unfavorable in terms of traffic safety.
It is an object of the present invention to provide a vehicle lighting apparatus adapted to illuminate correctly following the vehicle speeds.
According to the present invention, there is provided a vehicle lighting apparatus comprising lamp deflection angle controlling means which includes a steering angle sensor for detecting the steering direction of the vehicle and controls changes of the deflection angle of the direction of radiation of a lamp based on the output from the steering angle sensor, characterized in that there is provided a vehicle speed sensor for detecting the traveling speed of the vehicle and the lamp deflection angle controlling means is adapted to control the maximum deflection angle of the lamp based on the vehicle speed detected by the vehicle speed sensor. The lamp deflection angle controlling means is adapted in such a manner that the maximum deflection angle is 0xc2x0 when the vehicle is almost in a state of coming to stop and the maximum deflection angle decreases with increase in vehicle speed when the vehicle is in a cruising state at least at a prescribed speed. Further, the lamp deflection angle controlling means is preferably constructed so that the maximum deflection angle increases with increase in vehicle speed when the vehicle is in the transitional traveling state between the state of almost coming to stop and the cruising state.
According to the present invention, when the vehicle is in the state of almost coming to stop, by setting the maximum deflection angle of the lamp to 0xc2x0, the direction of radiation of the lamp is fixed in the straight ahead direction at the time of crawling, or being halted or parked, or at the time of putting the vehicle into a garage. Therefore, the adjacent area of the motor vehicle may be illuminated stably to prevent the motor vehicles or pedestrians passing nearby from being dazzled, and unpleasant feeling due to a large deflection of the direction of radiation of the headlamp may be prevented. When the vehicle is in the state of cruising almost at a high speed, the maximum deflection angle is suppressed with increase in vehicle speed, and thus the deflection angle of the lamp is controlled within the angle range around the straight ahead direction so that the area around the straight ahead direction at a corresponding distance in the traveling direction can be illuminated irrespective of the steering state of the vehicle, thereby preventing lateral fluctuation of the deflecting angle of the lamp. When the speed is gradually reduced, since the restrains on the maximum deflection angle is alleviated, the area immediately in front of the vehicle in the traveling direction may be illuminated correctly even on the curved road. In addition, since the maximum deflection angle signal is limited in accordance with reduction in vehicle speed when the vehicle is in the transitional traveling state between the halted state and the cruising state, continuity of variations in the maximum deflection angle between the halted state and the cruising state may be maintained, and thus sudden changes of the direction of radiation of the lamp at the time of stop and departure may be prevented so as not to give fear of insecurity to the occupant.